private void BtnUpdate_Click(object sender, RoutedEventArgs e)
        {
            member updateMemeber = (from m in _db.member
                                    where m.Id == id
                                    select m).Single();

            updateMemeber.name   = textBoxName.Text;
            updateMemeber.Gender = comboBoxGender.Text;
            _db.SaveChanges();
            MainWindow.datagrid.ItemsSource = _db.member.ToList();
            this.Hide();
        }
        private void BtnInsert_Click(object sender, RoutedEventArgs e)
        {
            member newMember = new member()
            {
                name   = textBoxName.Text,
                Gender = comboBoxGender.Text
            };

            _db.member.Add(newMember);
            _db.SaveChanges();
            MainWindow.datagrid.ItemsSource = _db.member.ToList();
            this.Hide();
        }